Perfect Bit Research Articles

Multiple-symbol noncoherent learning detection of coded QAM signals in IEEE 802.15.3 Wireless Multi-media Networks

We consider the noncoherent deep learning problem for coded signal detection under the phase noncoherent channels for remote home healthcare applications with high data rate. In particular, a multiple-symbol noncoherent learning detection (MNLD) scheme based on neural networks is proposed for low-density parity-check (LDPC) coded noncoherent quadrature amplitude modulation (QAM) signals in IEEE 802.15.3 Wireless Multi-media Networks. Our derivation shows that extensive operations for the first kind zero-order modified Bessel function is unavoidable for the implementation of the optimal bit log-likelihood ratio (LLR) for decoding in traditional multiple-symbol detection (MSD) scheme. The perfect estimation of the channel state information (CSI), i.e., a priori information about the variance of the additive white Gaussian noise (AWGN), is also required for the receiver. This is clearly not computationally practical for Wireless Multi-media Networks. Consequently, we developed an improved approach based on feed-forward neural networks to accurately calculate the bit LLR. Furthermore, to decrease the generation size of training set and thus increase the training speed of the proposed neural networks, we uniformly quantize the continuous carrier phase offset (CPO), which is random and unknown, into discrete status. Our simulation results verify the learning efficiency of this simplified training-set generation configuration. The decoding convergence is successfully accelerated and much performance gain is finally achieved when compared with traditional decoding using the perfect bit LLR. This is clearly critical for high reliable transmission of home healthcare information.

WI-MAX NETWORK SIMULATION FOR SALAHADDIN UNIVERSITY NEW CAMPUS

Wireless Networks became very important in this latest decade and especially Wi-Max system because of high bit rate, handover flexibility and longer distance of mobility. Signal strength and coverage is one of the challenges for this systems which leads to affect directly on Quality of Service (QoS), this paper is an attempt to design and study of Wi-Max network for a certain coverage area, testing the coverage of the signal for the area that can hold the sufficient amount of data with less latency has been studied depending upon the Wi-Max advanced specification and data stream behavior benefit’s, some Wi-Max parameters like coverage, quality of service, data rate are optimized, the study and design has been done using OPNET modeler used in the a simulation of the certain coverage area, in this paper the new campus of university of Salahaddin has been used on supposed area of about 4 X4 km. The results show a perfect bit rate as a bit stream for the global characteristics in which is sufficient to the students and teachers of the university in addition of providing the mobility by high performance. It is needed to design a wireless computer network to Salahaddin University to improve mobility and to let the teachers and students to stay connected at any time in any university location Especially with the nowadays learning techniques and requirements which needs both teacher and students to be online with each other especially like E-learning and online remount learning especially with the COVID-19 university campus blocking. Therefore, it is needed to cover overall area of the university campus and with additional coverage that exceed the university boundaries to improve the reliability of the hall network and to insure the required coverage area. To do that is very efficient to design an advanced computer network like Wi-Max with the most powerful and advanced hardware capabilities to full-fit the teachers and students requirement of fast net browsing and download in addition in e-learning bases it is very regular to use video conferencing or video streaming which normally needs a very fast network data transfer

Decode‐and‐forward polar coding scheme for receive diversity: a relay partially perfect retransmission for half‐duplex wireless relay channels

Recently, it is shown that the channel polarisation phenomenon of Arikan's polar codes with their original multilevel construction happens in several levels with perfect, partially perfect and useless bit channels. On the basis of this construction, this study aims to illustrate design principles and decoding steps of cooperative decode-and-forward polar coding schemes for half-duplex relay channel. In these schemes, the authors consider the use of relay retransmission of partially perfect bit channels in time-division process. The source node transmits its polar-coded information to both the relay and the destination nodes during the first time slot. For the second transmission period, the relay first decodes the source signal then after reconstruction of the polarisation matrix, the extracted partially perfect bit channels are recoded using another polar code and finally transmitted to the destination node. At destination, the signals received from both source and relay nodes are processed by using multi-stage successive cancellation decoding for retrieving the original information bits. They demonstrate via numerical results that by carefully constructed polarisation matrix at relay node, their cooperative polar coding schemes can achieve better performances than other previous schemes.

The expected bit complexity of the von Neumann rejection algorithm

In 1952, von Neumann introduced the rejection method for random variate generation. We revisit this algorithm when we have a source of perfect bits at our disposal. In this random bit model, there are universal lower bounds for generating a random variate with a given density to within an accuracy $\epsilon$ derived by Knuth and Yao, and refined by the authors. In general, von Neumann's method fails in this model. We propose a modification that insures proper behavior for all Riemann-integrable densities on compact sets, and show that the expected number of random bits needed behaves optimally with respect to universal lower bounds. In particular, we introduce the notion of an oracle that evaluates the supremum and infimum of a function on any rectangle of $\mathbb{R}^{d}$, and develop a quadtree-style extension of the classical rejection method.

On Symbol Versus Bit Interleaving for Block-Coded Binary Markov Channels

We examine bit- and symbol-interleaving strategies for linear nonbinary block codes (under bounded-distance decoding) over the family of binary additive noise finite-state Markov channel (FSMC) models with memory. We derive a simple analytical sufficient condition under which perfect (i.e., with infinite interleaving depth) symbol interleaving outperforms perfect bit interleaving in terms of the probability of codeword error (PCE). It is shown that the well-known Gilbert-Elliott channel (GEC) with positive noise-correlation coefficient and the recently introduced Markovian queue-based channel (QBC) of memory M satisfy this condition. This result has widely been illustrated numerically (without proof) in the literature, particularly for the GEC. We also provide examples of binary FSMC models for which the reverse result holds, i.e., perfect bit interleaving outperforming perfect symbol interleaving. Finally, a numerical PCE study of imperfect symbol-interleaved nonbinary codes over the QBC indicates that there is a linear relationship between the optimal interleaving depth and a function of a single parameter of the QBC.

SSFBG-based decorrelator for MUI rejection in synchronous optical CDMA systems

A superstructured fibre Bragg grating (SSFBG) decorrelator for rejecting multi-user interference (MUI) in a synchronous optical code division multiple access (OCDMA) system is proposed and investigated. The decorrelator is formed by appropriately defining the superstructure of a weak fibre Bragg grating. Theoretical results arrived at using coupled mode theory show that it is possible to make the MUI practically zero at the sampling instant provided there is perfect bit synchronisation among the users accessing the OCDMA system. A theoretical investigation on the degradation of optical signal to interference ratio (OSIR) is also conducted by statistically modelling the jitter likely to result in the bit synchronisation mechanism of the system.

Comparison of diversity with simple block coding on correlated frequency-selective fading channels

We investigate the effects of correlation on the performance of diversity systems in wideband wireless radio environments. Specifically, the average bit error rate (BER) performance of M-ary differential phase shift keying (MDPSK) on correlated frequency-selective slow Rayleigh fading channels is analyzed. A two-branch diversity receiver with postdetection equal gain combining is considered. Nyquist pulse shaping is used and differential detection is employed at the receiver. The effects of cochannel interference on the system performance are assessed using a Gaussian interference model. To further enhance the system performance, the effects of combined diversity and forward error correction (FEC) coding on the average BER are investigated. Results using short cyclic block codes with perfect bit interleaving are obtained. The effects of the root mean square (RMS) delay spread, the amount of correlation, and the level of modulation, M, on the average BER are investigated in detail for both coded and uncoded systems. The results show that dual branch diversity combining with a correlation coefficient of 0.5 outperforms (in terms of BER) short block codes with perfect bit interleaving, and that combined diversity and coding strategies are effective in combatting the effects of frequency-selective fading.